Database.PostgreSQL.Query.TH.SqlExp

QQ

sqlExp :: QuasiQuoter

Maybe the main feature of all library. Quasiquoter which builds SqlBuilder from string query. Removes line comments and block comments (even nested) and sequences of spaces. Correctly works handles string literals and quoted identifiers. Here is examples of usage

>>> let name = "name"
>>> let val = "some 'value'"
>>> run [sqlExp|SELECT * FROM tbl WHERE ^{Identifier name} = #{val}|]
"SELECT * FROM tbl WHERE \"name\" = 'some ''value'''"

And more comples example:

>>> let name = Just "name"
>>> let size = Just 10
>>> let active = Nothing :: Maybe Bool
>>> let condlist = catMaybes [ fmap (\a -> [sqlExp|name = #{a}|]) name, fmap (\a -> [sqlExp|size = #{a}|]) size, fmap (\a -> [sqlExp|active = #{a}|]) active]
>>> let cond = if L.null condlist then mempty else [sqlExp| WHERE ^{mconcat $ L.intersperse " AND " $ condlist} |]
>>> run [sqlExp|SELECT *   FROM tbl ^{cond} -- line comment|]
"SELECT * FROM tbl  WHERE name = 'name' AND size = 10  "

Types

data Rope

Internal type. Result of parsing sql string

Constructors

RLit Text

Part of raw sql

RComment Text

Sql comment

RSpaces Int

Sequence of spaces

RInt FieldOption Text

String with haskell expression inside #{..} or #?{..}

RPaste Text

String with haskell expression inside ^{..}

Instances

Eq Rope

Defined in Database.PostgreSQL.Query.TH.SqlExp

Methods

(==) :: Rope -> Rope -> Bool

(/=) :: Rope -> Rope -> Bool

Ord Rope

Defined in Database.PostgreSQL.Query.TH.SqlExp

Methods

compare :: Rope -> Rope -> Ordering

(<) :: Rope -> Rope -> Bool

(<=) :: Rope -> Rope -> Bool

(>) :: Rope -> Rope -> Bool

(>=) :: Rope -> Rope -> Bool

max :: Rope -> Rope -> Rope

min :: Rope -> Rope -> Rope

Show Rope

Defined in Database.PostgreSQL.Query.TH.SqlExp

Methods

showsPrec :: Int -> Rope -> ShowS

show :: Rope -> String

showList :: [Rope] -> ShowS

Parser

ropeParser :: Parser [Rope]

parseRope :: String -> [Rope]

squashRope :: [Rope] -> [Rope]

Removes sequential occurencies of RLit constructors. Also removes commentaries and squash sequences of spaces to single space symbol

Template haskell

sqlQExp

Arguments

:: String

-> Q Exp

Expression of type SqlBuilder

Build expression of type SqlBuilder from SQL query with interpolation

sqlExpEmbed

Arguments

:: String

file path

-> Q Exp

Expression of type SqlBuilder

Embed sql template and perform interpolation

let name = "name"
    foo = "bar"
    query = $(sqlExpEmbed "sqlfoobar.sql") -- using foo and bar inside

sqlExpFile :: String -> Q Exp

Just like sqlExpEmbed but uses pattern instead of file name. So, code

let query = $(sqlExpFile "foo/bar")

is just the same as

let query = $(sqlExpEmbed "sqlfoobar.sql")

This function inspired by Yesod's widgetFile